The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.


Diphenhydramine is not recommended during pregnancy unless it is clearly indicated. There is limited safety information from human studies that have looked at the use of diphenhydramine during pregnancy, but available studies indicate that the risk of harm in the developing baby remains unknown. Nursing infants exposed to diphenhydramine are at risk of drowsiness or slowed breathing; use of this medication while breastfeeding is not recommended. This medication should be used with caution if administered in pregnant women or nursing mothers.

What is diphenhydramine?

Diphenhydramine is a first generation antihistamine medication, currently available as generic and brand name (e.g. Benadryl) medications. Diphenhydramine is available in tablet, chewable tablet, capsules, elixir, liquid, syrup, injection, and oral strips and is taken once every 4-8 hours or once nightly if used for insomnia. It is available as an over-the-counter and prescription medication. 

What is diphenhydramine used to treat?

Diphenhydramine is used to treat allergic reactions, temporarily relieve insomnia, and treat symptoms of upper respiratory allergies including sneezing, runny nose, itchy nose or throat, itchy skin, and watery eyes in adults and children over 2 years of age. Diphenhydramine can also be used to prevent motion sickness and treat symptoms of Parkinson’s disease. Because it can cause sleepiness, it is sometimes used for insomnia.

How does diphenhydramine work?

Diphenhydramine works by preventing histamine from binding to receptors on cells in the respiratory tract, gastrointestinal tract, or blood vessels. Interruption of histamine binding prevents the inflammation and activation of the immune system that causes allergy symptoms. First generation antihistamines such as diphenhydramine can cause drowsiness or sleepiness.

If I am taking diphenhydramine, can it harm my baby?

Diphenhydramine should not be used during pregnancy unless it is clearly indicated. Other antihistamine medications may be recommended instead during pregnancy. There are limited human studies that have looked at the safety of this medication in pregnancy. Available studies have not proven a direct association between diphenhydramine use during pregnancy and an increased risk of birth defects. Some studies suggest there may be benefits associated with antihistamine use during pregnancy. A recent review of 50 scientific articles found most types of antihistamines used during pregnancy do not increase the risk of birth defects in newborns. 

Evidence from animal studies of diphenhydramine:

When given to pregnant rats at much larger doses than the maximum recommended human dose, diphenhydramine was found to cause increased skeletal weakness as well as altered development and sexual behavior in the babies. 

Evidence for the risks of diphenhydramine in human babies:

At least 2 large studies of women exposed to diphenhydramine during the first trimester of their pregnancy found no evidence to link birth defects to diphenhydramine use in early pregnancy. One study conducted in 1974 reported a possible correlation between diphenhydramine use in the first trimester and an increased risk of cleft palate in newborns. A later study found an increased risk of cleft palate, neural tube defects, limb defects, stomach defects, heart defects, and skull defects with first trimester exposure to diphenhydramine. Follow-up studies found no association between first trimester diphenhydramine use and birth defects, with one of the studies finding a decreased risk of birth defects with antihistamine use during pregnancy. Data from the Swedish Medical Birth Registry suggest antihistamine exposure during pregnancy may slightly decrease the risk of heart defects, premature birth, and low birth weight. The National Birth Defects Prevention Study (1997-2003) and the Slone Epidemiology Centers Birth Defects Study (1998-2010) both found no association between first trimester antihistamine exposure and risk of birth defects. There have been reports of retrolental fibroplasia, an eye disorder causing blindness, with antihistamine use 2 weeks before delivery in premature newborns. There has been one report of neonatal withdrawal in an infant exposed to diphenhydramine in utero.

Bottom line: Diphenhydramine should not be used during pregnancy unless clearly indicated. Human and animal studies suggest there may be negative side effects associated with diphenhydramine use during pregnancy, but the risk of birth defects is not expected to increase.

If I am taking diphenhydramine and become pregnant, what should I do?

If you are taking diphenhydramine and become pregnant, you should contact your doctor immediately. Your doctor will determine if your medication is medically necessary, or if it should be discontinued until after the birth of your baby. Diphenhydramine has been associated with increased uterine activity in pregnant women that can increase the risk of premature labor.

If I am taking diphenhydramine, can I safely breastfeed my baby?

Breastfeeding is not recommended in women who are taking diphenhydramine or other first generation antihistamines. Case reports detail drowsiness in nursing infants exposed to this medication. Nursing infants exposed to diphenhydramine should be monitored for signs of drowsiness or irritability. Premature newborns and infants may be at a higher risk of developing negative side effects with diphenhydramine exposure. Women who are breastfeeding infants and require an antihistamine are generally advised to take a second generation antihistamine. Occasional dosing of diphenhydramine at night after the last breastfeed may decrease the risk of any negative side effects in nursing infants. Diphenhydramine may decrease milk production particularly if taken before lactation is established in new mothers or if high doses are administered to women. It is important to weigh the risks versus benefits before taking this medication while nursing an infant. 

Bottom line: Breastfeeding is not recommended in women who are taking diphenhydramine. In breastfeeding moms taking this medication, caution is advised due to unknown effects on breastfeeding babies.

If I am taking diphenhydramine, will it be more difficult to get pregnant?

Studies in rats and rabbits given doses up to 5 times greater than human doses found no evidence of  impaired fertility. 

If I am taking diphenhydramine, what should I know?

Diphenhydramine should only be used during pregnancy if clearly indicated. Human studies suggest there is no increased risk of birth defects with first trimester exposure to this medication.a preferred antihistamine during pregnancy.

Breastfeeding is not recommended in women who are breastfeeding infants due to the potential risk of drowsiness and slowed breathing.

If I am taking any medication, what should I know?

This report provides a summary of available information about the use of diphenhydramine during pregnancy and breastfeeding. Content is from the product label unless otherwise indicated.

You may find Pregistry's expert report about allergic rhinitis here, reports about various other health conditions as well as the individual medications used to treat allergies and other conditions here.   Additional information can also be found in the resources below. 

For more information about diphenhydramine during and after pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or check the following link: Diphenhydramine Prescribing Information

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Last Updated: 24-03-2019
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.